Extrusion machine

ABSTRACT

A thermal-extrusion machine is disclosed with an extrusion head for the production of metal sections and tubes, particularly of light copper-based alloys. The extrusion head comprises a core coaxially received in an aperture of an associated die. The core is supported by bridging means in the form of webs angularly equispaced about the axis thereof. A chamber is formed in the head and downstream of the webs, to transverse section of the chamber being sufficiently small to let the pressure of the material being extruded fuse the strands formed by the material passing the webs and reuniting in the chamber.

Uted States Patent Creuzet Jul 31 1973 EXTRUSION MACHINE Primary Examiner-Charles W. Lanham 76 Inventor. Robert Creuzet Rt d Bl ss 47 1 Marmande e y ac Assistant ExaminerRobert M. Rogers Attorneyl(arl F. Ross [22] Filed: Dec. 4, 1970 Appl. No.: 97,418

[57] ABSTRACT A thermal-extrusion machine is disclosed with an extrusion head for the production of metal sections and tubes, particularly of light copper-based alloys. The extrusion head comprises a core coaxially received in an aperture of an associated die. The core is supported by bridging means in the form of webs angularly equispaced about the axis thereof. A chamber is formed in the head and downstream of the webs, to transverse section of the chamber being sufficiently small to let the pressure of the material being extruded fuse the strands formed by the material passing the webs and reuniting in the chamber.

4 Claims, 11 Drawing Figures PATENIEDJum I ma SHEET 1 BF 5 INVENTOR:

Robert CRE UZET PATENTEBJUL 31 ms SHEET 2 BF 5 co m m m H J J .25 A4 5 1h INVENTOR Robert CREUZET aw Attorney PATENTED JUL 3 I SHEET 3 BF 5 mdE INVENTOR:

Robert CREUZET PATENIED JUN 1 SHEET I 0F 5 FIG.9

INVENTOR:

Robert cmauzm 9 BY m l Rm Attorney PATENIEDJUW I915 3.748.885

SHEET 5 BF 5 FIG 11 FIG. 10

INVENTOR:

Robert CREUZET BY (Karl 6R0 Attorney EXTRUSION MACHINE My present invention relates to the manufacture by thermal extrusion of fusible tubes, sections or analogous elements of metal compositions, in particular light alloys.

The manufacture of tubes or the like by the ordinary extrusion apparatus, which comprises a core coaxially mounted in a die aperture to form an annular extrusion gap, is known not to give satisfactory results when a high degree of structural precision is required, for example in the case of the manufacture of tubes or other elements intended to be used in aeronautic and aerospace construction.

The use of a short core has been proposed to overcome this disadvantage but such a core' must be connected to a body by bridging portions as webs which in the course of extrusion divide the material into strands. Even though an extrusion head of this type may give satisfactory results in numerous cases, it does not give such results for the extrusion of certain alloys in particular light copper-base alloys.

Until now, it has not been possible to obtain elements of light copper-base alloys of a satisfactory quality by thermal extrusion which is the reason for these elements not being accepted in constructions where safety requirements are very stringent.

The extrusion head according to the invention overcomes this problem. According to a feature of my invention the chamber into which emerge the strands of material during extrusion and after passing beyond the bridging portions supporting the core has a transverse section sufficiently small in order that, under the effect of extrusion of the material the pressure within the material in the chamber is sufficiently high to fuse the seams resulting from the joining in the chamber of the strands that have passed beyond the bridging portions.

I have found that extrusion products of a uniform quality are obtained in this manner even with supposedly non-weldable light copper-base alloys such as for instance, AU4G, AU4G1, AU4SG, AUZGN, etc..

Advantageously, the arrangement and the configuration of the bridging portions or webs is such that from the extrusion piston the material progresses towards the axis of the head with a transverse flow section which progressively decreases towards the chamber for reuniting the strands.

The description which follows, given by way of example, refers to the accompanying drawing in which:

FIG. 1 is a front view of a head of an extrusion machine according to the invention;

FIG. 2 is a rear view thereof;

FIG. 3 is a view in section along line 3-3 of FIG. 1;

FIG. 4 is a view in section along line 4-4 of FIG. 1;

FIG. 5 is a view in section along line 5-5 of FIG. 2;

FIG. 6 is a view in transverse section of the contents of the extrusion cylinder taken along line 6-6 in FIG.

FIG. 7 is a view similar to that of FIG. 6 as taken on the line 7-7 of FIG. 5;

FIG. 8 is a view similar to the two preceding Figures as taken along line 8-8 of FIG. 5;

FIG. 9 is a view similar to the preceding Figures but taken along line 9-9 of FIG. 5;

FIG. 10 is a view similar to the preceding Figures but taken along line 10-10 of FIG. 5; and;

FIG. 11 is a view similar to the preceding views as taken along line 11 ll of FIG. 5.

As shown in FIG. 5, an annular clearance or extrusion gap 10 is provided between a central core 13 and a discharge aperture a of the die 12. The cylindrical surface 14 of the aperture 11 is confronted by, the needle 13 has an outer cylindrical surface 15 of core 13.

The core 13 is part of an extrusion head 17 having an annular base 18 with a cylindrical outer surface 19 in co-operating contact with the cylindrical inner surface 20 of a chamber or cylinder 21. The base 18 has an outer rib 22 whose inner surface 23 engages with a cylindrical shoulder 24 of the body of the die 12.

The core 13 is connected to the base 18 by several (here four) webs or bridging portions, for example four 25,, 25 25 25 angularly equispaced about the axis 16. Each wing has a body 26 bounded by two planar faces 27 and 28 which are parallel in the portion remote from the base 18 and converge along incurved flanks 29 and 30 which meet along a front edge 31 in axial planes 32 and 33, respectively (FIG. 2).

The section of a web body 26 cut by such a plane is bounded by an ridge line 34 relative to the axis 16; the outer surfaces of the webs meet along a central surface 35 with a rounded tip or rear end 36 substantially centered on the axis 16.

The opposite wing surface 35' is joined to the cylindrical surface 15 of the core 13 by an incurved surface 36', lying substantially in the transverse plane passing through the edge 31, and approach is the annular transverse face 37 of the die along a surface 38 which has substantially rectilinear and may therefore be regarded as frustoconical. These generatrices, as shown in FIG. 5, are substantially parallel to the confronting flanks 29, 30 of the web.

When the cylinder 21 is filled with an extruding composition 42 as diagrammatically indicated in FIG. 3, for example a metal alloy, and this composition is subjected to an action of the extrusion piston 41, the more or less viscous mass heated within the cylinder divides into segments passing around the webs 25 -25 The circular cross section of the mass of the extruding composition upstream of the tip portion 36 equals that of the chamber 21 as is shown in FIG. 6. The cross-section in the plane 7-7 has a surface area slightly less than that of the section in the line plane 6-6, the non-shaded part shown in FIG. 7 correspond to the webs which at this point have the shape of a cross with four arms.

As the webs progressively diverge from one another in proportion to the distance from the tip portion 36, the mass effectively divides into four spatially separated strands 42,, 42 42 42 (FIG. 8) as soon as it passes through the transverse section perpendicular to the axis 16 which is tangent to the outer face of the annular base 18 forming the support for the bridging portions.

The cross-section of the strands progressively narrows in conformity with the incurved shapes of the opposite web flanks or faces 29 and 30, the section of the strands then becoming that shown in FIG. 9.

As the material 42 advances beyond the transverse section corresponding downstream'end 31 of the central web structure, it an annular channel defined by the outer surface of the core body and by the inner surface 38 of the annular base so as to assume a cloverleaf shape 42' as shown in FIG. 10.

The strands intertwine with one another in this chamber whose clearance is sufficiently small so that the extrusion pressure exerted by the piston 41 in the cylinder causes a fusing at the seams where the strands meet. This results in the joining of the strands so that during the extrusion proper ie the passage through the gap 10, the homogeneity of the material of the resulting tubular object 42" is assured to the same extent as if no division into strands had taken place (see FIG. 11).

l have found that, by the use of an extrusion head according to the invention, tubes can be formed which not only profit from the precision owing to the use of a short core depending from bridging portions of an extrusion head, but which also have the same continuity as those obtained from a mass not divided into strands during compression.

The arrangement and the configuration of the arms or the bridging portions are chosen as a function of the metal section or tube to be produced and also of the nature of the alloy to be extruded in order to obtain the best grain structure.

The number of bridging portions may vary, according to the article to be produced, from a single one to several dozens.

An extruded article of light copper-base alloys according to the invention is distinguishable from those that have been obtained from standard extrusion heads by the precision of its configuration, perfectly concentric internal and external surfaces in the case of a tube and exact dimensions and thicknesses in the case of a different profitt, as well as by its homogeneity, the intertwining seams resulting from the joining of the strands being practically unnoticeable owing to the welding under pressure during extrusion.

What is claimed:

1. An extrusion head for producing tubular objects from a fusible metalliccomposition, comprising:

a cylinder adapted to be filled with a heated metallic mass;

an extrusiondie forming an end wall of said cylinder,

said die being provided with a discharge aperture;

a central core in said cylinder extending with allaround clearance into said aperture;

a support for said core in said cylinder, said support comprising an annular base adjacent said die and bridging means extending from said base to said core, said bridging means forming with said base a passage for said mass narrowlng progressively toward said opening, said bridging means'terminating short of said die whereby a annular channel larger than said aperture is formed between said passage and said aperture, said channel being bounded by an inner peripheral surface of said base converging toward said opening; and

plunger means in said cylinder for compressing said mass around said core and forcing the compressed mass through said passage and said channel into the clearance between said core and said die. an

2. An extrusion head as defined in claim 1 wherein said bridging means comprises a plurality of webs extending radially from said base to said core.

3. An extrusion head as defined in claim 2 wherein said webs have ridges remote from said die merging tangentially into said core at a rounded rear end thereof, each web having a profile bounded by flanks meeting at a front edge thereof.

4. An extrusion head as defined in claim 3 wherein said inner peripheral surface is generally frustoconical in cross-section and has generatrices substantially paralleling said flanks.

UMTED STATES PATENT eFmcE CERTEFECATEOF CQRREQTEGN Patent No. 3,748,885 ated 31 y 1973 lrvefitofls) Robert CREUZEIT It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, line "[76]" for "BLYSSAC" read eifss d-n -Signed and sealed this 5th day of February 1974.

(SEAL) Attest:

EDWARD M.FLETCI -IER ,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents 

1. An extrusion head for producing tubular objects from a fusible metallic composition, comprising: a cylinder adapted to be filled with a heated metallic mass; an extrusion die forming an end wall of said cylinder, said die being provided with a discharge aperture; a central core in said cylinder extending with all-around clearance into said aperture; a support for said core in said cylinder, said support comprising an annular base adjacent said die and bridging means extending from said base to said core, said bridging means forming with said base a passage for said mass narrow1ng progressively toward said opening, said bridging means terminating short of said die whereby a annular channel larger than said aperture is formed between said passage and said aperture, said channel being bounded by an inner peripheral surface of said base converging toward said opening; and plunger means in said cylinder for compressing said mass around said core and forcing the compressed mass through said passage and said channel into the clearance between said core and said die. an
 2. An extrusion head as defined in claim 1 wherein said bridging means comprises a plurality of webs extending radially from said base to said core.
 3. An extrusion head as defined in claim 2 wherein said webs have ridges remote from said die merging tangentially into said core at a rounded rear end thereof, each web having a profile bounded by flanks meeting at a front edge thereof.
 4. An extrusion head as defined in claim 3 wherein said inner peripheral surface is generally frustoconical in cross-section and has generatrices substantially paralleling said flanks. 